gbdev
A section on LCD artifacts may be useful
This would cover things such as blur/smearing/etc, including simple 2-frame blending effects, but also more complex behaviors. One of the more complex behaviors is as follows.
ISSOtm noticed an unexpected artifact in The Forest Hero, as described here:
Go into the hole shown at the beginning, then go up and down the stairs My DMG shows a bunch of vertical lines for some reason
Based on the belief that it was due to the brick tiles effectively toggling pixels between black/white on alternating frames I created the following test ROM. If you press A when this ROM is running the stripped tiles will essentially be xor'd every other frame, leading to a similar effect, which gets worse as there's more white in a given column.
It's not quite the same as the game because this is 50:50 white/black, but I believe it's the same effect.
(FLASHING WARNING: You probably don't want to press A with this ROM without frame blending enabled in an emulator, as it will flash very quickly.): vertical_smear.zip
LIJI produced mockups of the resulting effect on their GB Light with normal contrast:
as well as high contrast:
I'm unaware of an emulator which attempts to emulate this behavior at this time.
144p Test Suite's "Motion blur" test likewise shows a fadeout on DMG and MGB if you turn on stripes.
